Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional of U.S. Ser. No. 12/051,941 filed
on Mar. 20, 2008, now pending, which is a continuation of International
Patent Application No. PCT/CN2006/002413, with an international filing
date of Sep. 15, 2006, which is based on Chinese Patent Application No.
200510015209.6, filed on Sep. 27, 2005. The contents of all of the
aforementioned Applications, including any intervening amendments
thereto, are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to 5H-thioeno(3,4-c)pyrrole-4,6-dione
derivatives which are active as inhibitors of tumor necrosis factor (TNF)
released by cells, the preparation of these derivatives, as well as their
application as pharmaceutically-active ingredients.

[0009] At present, the disease most commonly linked to TNFα released
by tumor and host tissue is hypercalcemia, which is closely related to
malignant tumors (Calci. Tissue Int. (US) 46(Suppl.), S3-10 (1990)). It
has also been observed that immune response is closely related to an
increased concentration of TNFα in serum of the patient after bone
marrow transplantation (Holler et al., Blood, 75(4), 1011-1016 (1990)).

[0010] Fatal hyperacute neurogenic syndrome brainstem-type malaria, which
is the most dangerous type of malaria, is also linked to high levels of
TNFα in blood. When this kind of malaria occurs, the levels of
TNFα in serum are directly related to the disease, which often
occurs during an acute attack of malaria in patients (Grau et al., N.
Engl. J. Med. 320(24), 1586-91 (1989)).

[0011] TNFα also plays an important role in bone resorption diseases
including arthritis (Betolinni et al., Nature 319, 516-8 (1986)).
TNFα may stimulate bone resorption by stimulating the formation and
activation of osteoclast and inhibit the formation of bone, which was
shown both by in vitro and in vivo experiments.

[0012] TNFα plays an important role in chronic pneumonia, as well.
The storage of silicon-containing particles can cause silicosis.
Silicosis is a type of progressive respiratory failure, resulting from
fibrosis of pulmonary tissues. In an animal pathological model,
TNFα antibody can fully block the progress of lung fibrosis in mice
caused by silica dust (Pignet et al., Nature, 344:245-7 (1990)). It was
also proved that TNFα levels are abnormally high in serum of
animals with pulmonary fibrosis caused by silica dust or asbestos dust in
animal experiments (Bissonnette et al., Inflammation 13(3), 329-339
(1989)). Pathological research reveals that TNFα levels in
pulmonary tissues of patients with pulmonary sarcoidosis is much higher
than that of ordinary people (Baughman et al., J. Lab. Clin. Med. 115(1),
36-42 (1990)). This suggests that TNFα inhibitor could have a great
significance in the treatment of chronic pulmonary diseases and lung
injury.

[0013] One reason for inflammation occurring in the patient with
reperfusion injury may be abnormal levels of TNFα.

[0015] Besides, it has been shown that TNFα may start retroviral
replication including that of HIV-1 (Duh et al., Proc. Nat. Acad. Sci.,
86, 5974-8 (1989)). T-cells need to be activated before HIV invades them.
Once the activated T-cells are infected by virus (HIV), those T-cells
must remain in an activated state in order for the HIV virus genes are
able to express and/or replicate successfully. Cytokines, especially
TNFα, play an important role in the process of HIV protein
expression or viral replication controlled by T-cells. Inhibition of
TNFα production can in turn inhibit HIV replication in T-cells
(Poll et al., Proc. Nat. Acad. Sci., 87, 782-5 (1990); Monto et al.,
Blood 79, 2670 (1990); Poll et al., AIDS Res. Human Retrovirus, 191-197
(1992)).

[0016] cAMP can regulate many functions of cells, such as inflammation
response, including asthma, and inflammation (Lome and Cheng, Drugs of
the futune, 17(9), 799-807, 1992). When inflammation occurs, increased
cAMP concentration in white cells inhibits activation of white cells, and
then releases inflammation regulatory factors including TNFα so as
to exacerbate inflammation in patients. Consequently, the inhibition of
TNFα release can alleviate inflammation diseases including asthma.

[0017] Yu Yanyan et al, have found that TNFα plays an important role
in the process of liver necrosis in patients with viral hepatitis. (Yu
Yanyan etc., Chinese Journal of Internal Medicine 1996, 35:28-31). This
shows that TNFα inhibitors may play a great role in treatment of
chronic hepatic disease and liver injury.

[0018] Li Yingxu et al have found that levels of synthesis and secretion
of tumor necrosis factors in monocytes in the peripheral blood of
patients with chronic hepatic disease increase, which induces secretion
of other cytokines (for example, IL-1β, IL-6 and IL-8). All these
cytokines including tumor necrosis factors are all together involved in
the injury process of hepatocytes (Journal of Qiqihar Medical Colleg,
22(10):1119-1120, 2001). Their study results coincide with the
conclusions of Yoshioka, et al. (Hepatology, 1989, 10:769-777) and Wang
Xin, et al. (Chinese Journal of Infectious Diseases, 1997, 15(2):85-88).
It has also been found that thalidomide, the inhibitor of TNFα, is
able to inhibit TNFα secretion of monocytes in the peripheral blood
of hepatitis patients, which lays a foundation for the application of
TNFα inhibitors to treatment of hepatitis, cirrhosis and liver
cancer.

[0020] TNFα regulates the differentiation of B lymphocytes and
reinforces the cytotoxicity of natural killer cells (NK), so as to
involve in the regulation of immunel functions by means of activation of
macrophages and immunological stimulation of proliferation of
T-lymphocytes.

[0022] This invention is directed to 5H-thioeno(3,4-c)pyrrole-4,6-dione
derivatives and organic or inorganic salts thereof, preparation methods
thereof, and their application as pharmaceutically-active ingredients
useful as TNFα release inhibitors in cells.

[0023] The 5H-thioeno(3,4-c)pyrrole-4,6-dione derivatives of this
invention are encompassed by the general formula (I):

[0035] Among the 5H-thieno(3,4-c)pyrrole-4,6-dione derivatives represented
by formula (I), suitable as a pharmaceutically-active ingredients useful
as TNFα release inhibitors in cells are, without limitation, the
following compounds:

[0109] As a natural extension, this invention also includes various
metabolites and prodrugs of the compounds encompassed by formula (I).

[0110] When used as pharmaceutically-active ingredients, the compounds
encompassed by formula (I) may be R isomers, S isomers, or racemates.

[0111] When used as pharmaceutically-active ingredients, the compounds
encompassed by formula (I) may be in the form of a free base, or a
physiologically-acceptable inorganic salt, including a hydrochlorate, a
sulphate, a nitrate, or a phosphate, or an organic salt, including a
sulphonate, an acetate, a formate, a fumarate, a maleate, a citrate, a
tartrate, a malate, an ascorbate, a gluconate, a lactate, a succinate, or
a trifluoroacetate.

[0112] When used as pharmaceutically-active ingredients, the compounds
encompassed by formula (I) may be in the form of a hydrate of a free
base.

[0113] When used as pharmaceutically-active ingredients, the compounds
encompassed by formula (I) may be in the form of a hydrate of a
physiologically-acceptable salt.

[0114] This invention is directed further to a first method for preparing
a 5H-thioeno(3,4-c)pyrrole-4,6-dione derivative encompassed by formula
(I), comprising reacting a compound of formula (II) with a compound of
formula (III)

[0121] In more detail, this method comprises the following steps: [0122]
step 1: reacting a compound represented by formula (II) with a compound
represented by formula (III) to obtain a compound represented by formula
(IVA) or formula (IVB);

[0122] ##STR00076## [0123] step 2: reacting the compound represented
by formula (IVA) or formula (IVB) with a condensing agent in an aprotic
solvent to obtain a compound represented by formula (I).

[0124] After step 1, the obtained product, i.e., the compound represented
by formula (IVA) or formula (IVB), may be purified or may be used without
purification. The reaction mixture obtained after step 1 may be dried to
remove water. Step 1 and 2 may be conducted in situ (merged into one
step).

[0125] In step 1, the mol proportion between the amount of the compound
represented by formula (II) to that of the compound represented by
formula (III) is between 1.0:0.4 and 1.0:2.0; more particularly, between
1.0:0.6 and 1.0:1.5; and most particularly, between 1.0:0.8 and 1.0:1.2.

[0126] One or more organic bases and/or inorganic bases, including but not
limited to triethylamine, trimethylamine, pyridine, NaOH, KOH, LiOH,
Ca(OH)2, Na2CO3, K2CO3, Cs2CO3,
NaHCO3, KHCO3, Na3PO4, Na2HPO4,
NaH2PO4, K3PO4, K2HPO4, KH2PO4,
or a mixtures thereof, may be added to the reaction mixture in step 1, in
step 2, and/or if the steps are conducted in situ.

[0127] All reactions described herein is performed, without limitation, in
an organic solvent, such as dichloromethane, chloroform, acetone,
butanone, N,N-dimethylformamide, dimethyl sulfoxide, dimethoxyethane,
tetrahydrofuran, pyridine, and acetonitrile; and the reaction mixture may
be monophasic, biphasic, or multiphasic, with or without the addition of
phase transfer catalysts.

[0128] In step 2, the condensing agents appropriate for the preparation of
compounds shown as formula (I) include, but are not limited to
carbonyldiimidazole, DCC, EDC, SOCl2, PCl5, POCl3, or
acetic anhydride, or their mixture. In step 2, the ratio of the molar
amount of the condensing agent to the molar amount of the compound
represented by formula (II) may be between 0.5:1.0 and 4.0:1.0;
particularly, between 0.8:1.0 and 3.0:1.0; and more particularly between
1.0:1.0 and 1.5:1.0.

[0130] The temperature of the reaction mixture in step 2 may be maintained
at between 0° C. and 200° C.; more particularly at between
10° C. and 150° C., and most particularly at between
15° C. and 100° C.

[0131] When preparing the compound of formula (I) by this method, in step
1 and/or step 2, a pyridine derivative may be added as a catalyst. The
pyridine derivative is selected pyridine, 4-dimethylaminopyridine,
4-diethylaminopyridine, or 4-(1'-tetrahydropyrryl)pyridine. The molar
ratio of the pyridine derivative to the compound of formula (II) is
between 0.1 and 20 percent.

[0132] This invention is directed further to a second method for preparing
a 5H-thioeno(3,4-c)pyrrole-4,6-dione derivative encompassed by formula
(I) comprising reacting a compound represented by formula (V)

[0138] X represents a leaving group, such as Cl, Br, I, Ms, Ts, and so on.

[0139] The base is selected from an inorganic base including, but are not
limited to NaH, KH, CaH2, K2CO3, Na2CO3,
KHCO3, NaHCO3, Li2CO3, Cs2CO3, LiOH, KOH,
NaOH, Ca(OH)2, K3PO4, or K2HPO4, or an organic
base. The molar ratio of the base to the compound represented by formula
(V) is between 50% and 300%.

[0140] The reaction is performed, without limitation, in an organic
solvent, such as dichloromethane, chloroform, acetone, butanone,
N,N-dimethylformamide, dimethyl sulfoxide, dimethoxyethane,
tetrahydrofuran, pyridine and acetonitrile; and the reaction mixture may
be monophasic, biphasic, or multiphasic, with or without the addition of
phase transfer catalysts.

[0141] This invention is directed further to a method for preparing a
5H-thioeno(3,4-c)pyrrole-4,6-dione derivative represented by formula (I),
wherein R1 represents an amino group,

##STR00078##

comprising reducing a compound represented by formula (I) in a reduction
reaction, wherein R1 represents a nitryl to yield a compound
represented by formula (I), wherein R1 represents an amino. The
reduction reaction for reducing nitryl may be a catalytic hydrogenation.

[0143] The pressure range of hydrogen used in the hydrogenation reaction
is between 1 and 200 times the atmospheric pressure.

[0144] The temperature range for this reaction is between -30° C.
and 180° C.

[0145] The catalyst employed may be a metal such as Pd, Pt, Ru, Ni, etc,
their oxides, their salts, or their mixture.

[0146] During this reaction, acid may be added.

[0147] Further, the reduction reaction for reducing the nitryl in the
5H-thioeno(3,4-c)pyrrole-4,6-dione derivatives represented by formula (I)
may employ a reducing agent selected from a non-metal salt; a hydride,
such as borohydride; a metallic salt, such as tin protochloride; or a
reducing metal and a hydrogen source, such as zerovalent iron powder and
a protic acid.

[0151] The invention is directed further to pharmaceutical compositions
comprising at least one compound represented by formula (I) and a
diluent, excipient, loading agent, solvent, colorant, and/or adhesive.
The selection of adjuvants and dosage is decided by a skilled artisan
taking into account the mode of administration, e.g., gastrointestinal,
intravenous, abdominal, dermal, intramuscular, nasal, ocular, pulmonary,
anal, vaginal, transdermal, etc.

[0152] When used as pharmaceutically-active ingredients, the compounds
represented by formula (I) may be made into a rapid release, slow
release, and common medicament forms.

[0153] When used as pharmaceutically-active ingredients, the dose of the
compounds represented by formula (I) depends on administration routines,
administration strategies, disease types, detailed condition of patients,
etc.

[0154] When used as pharmaceutically-active ingredients, the compounds
represented by formula (I) may be formulated in combination with other
appropriate pharmaceutically-active compounds.

[0155] Cytokine TNFα released by PBMCs in the peripheral blood after
lipid polysaccharide (LPS) stimulation in vitro was studied. The
followings are experimental protocols for studying cytokine TNFα
released by PBMCs, which are inhibited by compounds of the invention.

[0156] PBMCs were obtained from blood of at least three volunteers after
heparin treatment, using gradient extraction. PBMCs were collected and
washed three times with a 1640 medium (10% calf serum, 2 mM L-glutamine,
100 mM mercaptoethanol, 50 μg/mL streptomycin, 50 U/mL penicillin),
then placed into wells of a 24-well cell culture plate. The concentration
was adjusted to 1×106 cells/mL with 1640 culture medium. Test
compounds, as shown in Table 1, were dissolved in dimethylsulfoxide at a
given concentration. The resultant solution was added to the cell culture
medium and the culture plate was placed in a CO2 incubator (5%
CO2, 90% humidity) for 1 hour. Then, LPS (Sigma) was added and its
concentration was adjusted to 0.1 μg/mL (except for the control).

[0157] After a 20 hr incubation period, the content of TNFα in
supernatant of the above PBMC culture medium was assayed by ELISA kit
(America Genzyme Co), using standard method. The measured value of the
control well (not treated with active components), and the measured value
of the test wells containing the test compounds was used to calculate the
TNFα inhibition rate. The concentration of compounds giving a 50%
TNFα inhibition (IC50 value) was calculated using nonlinear
regression analysis. Each concentration was determined twice and an
average value was calculated. Results are illustrated in Table 1.

[0160] To a 2000 mL three-necked flask under inert gas, equipped with a
mechanic stirrer, and a reflux condenser, 96.80 g of
3,4-dibromothiophene, 104 g cuprous cyanide, and 100 mL anhydrous DMF
were added. After refluxing for 4 h, the reaction mixture was cooled down
to room temperature; and a solution obtained by dissolving 400 g of
FeCl3.6H2O in 700 mL of hydrochloric acid (1.7 M) was added
into the reaction mixture and allowed to react for 30 min at
60-70° C. After the reaction mixture was fully cooled, 500 mL DCM
was added. The reaction mixture was divided into 300 mL portions and
extracted with DCM (2×300 mL). The DCM layers were combined. The
extracts were divided into 600 mL portions, washed successively with
2×50 mL 6N hydrochloric acid, water, saturated Na2CO3
aq., and brine; dried over anhydrous MgSO4, filtered, and evaporated
to dryness to obtain a yellow solid. The solid was washed with a mixture
of ethyl acetate:petroleum ether=1:1, and filtered to obtain a white
solid (21 g). 1H NMR (CDCl3): δ 8.07 (s, 2H).

Example 2

Thiophene-3,4-dicarboxylic acid

##STR00080##

[0162] To a 500 mL round bottom flask equipped with an electromagnetic
stirrer and a reflux condenser, 15.978 g of 3,4-dicyanothiophene, 43.997
g KOH, and 174 mL glycol were added; and the mixture was refluxed for 4
h. After the reaction mixture was cooled, 350 mL water was added, and the
aqueous layer was extract with ether (2×100 mL). The layers were
separated, the aqueous layer was cooled down in an ice bath, and excess
strong hydrochloric acid was added until a white precipitate appeared.
The solid was filtered and dissolved in 2000 mL of ether. The aqueous
layer was extracted with ether (3×300 mL). Organic layers were
combined, dried over anhydrous MgSO4, filtered, and evaporated to
dryness. 15 g of white solid was obtained and recrystallized from water.
1H NMR (DMSO-d6): δ 10.35 (brs, 2H, COOH), 8.17 (s, 2H);
MS (m/z): 171 (M-1).sup.+.

Example 3

Thieno(3,4-c)furan-1,3-dione

##STR00081##

[0164] To a 250 mL round bottom flask under inert atmosphere, equipped
with an electromagnetic stirrer, and a reflux condenser, 15 g of
thieno-3,4-dicarboxylic acid and 120 mL of acetic anhydride were added.
The mixture was refluxed for 3 h, evaporated to dryness to remove
solvent. 13 g of deep brown solid were obtained.

Example 4

2-nitrothiophene-3,4-dicarboxylic acid

##STR00082##

[0166] To a 250 mL round bottom flask under inert atmosphere, equipped
with an electromagnetic stirrer, 40 mL of fuming nitric acid (95%) were
added. The flask was cooled down to between 0 and 5° C. 10 g of
thieno(3,4-c)furan-1,3-dione was added in portions (1 g at a time), and
then the mixture was allowed to react for 30 min while maintaining the
temperature. A yellow solid precipitated out. The reaction mixture was
poured into 80 g ice water mixture, and extracted with ethyl acetate
(3×100 mL). Organic layers were combined, washed with water
(2×50 mL) and brine, dried over anhydrous MgSO4, filtered, and
evaporated to dryness to remove the solvent. A yellow solid (10 g) was
obtained. MS (m/z): 216 (M-1).sup.+.

Example 5

4-nitrothieno(3,4-c)furan-1,3-dione

##STR00083##

[0168] To a 250 mL round bottom flask under inert atmosphere equipped with
an electromagnetic stirrer, 10 g of 2-nitrylthieno-3,4-dicarbonyl acid
and 100 mL of acetic anhydride were added. The mixture was stirred for 3
h, evaporated to dryness to remove the solvent, and a deep brown solid (9
g) was obtained.

[0172] 7.86 g of benzyl 2,6-dioxopiperidin-3-yl carbamate were dissolved
in 30 mL of THF and 30 mL of methanol. 0.786 g of 10% Pd/C were added to
the above solution. The reaction mixture was allowed to react under a
flow of hydrogen at room temperature for 2 h, filtered to remove the
catalyst, and evaporated to dryness to remove the solvent. A light blue
solid (3.818 g) was obtained.

Example 8

Tert-butyl 2,6-dioxopiperidin-3-yl carbamate

##STR00086##

[0174] 11.4 g BOC-L-glutamine were dissolved in 120 mL of anhydrous THF.
7.776 g of CDI and a catalytic quantity of DMAP was added to the
solution. The reaction mixture was refluxed and reacted for 6 h. After
being cooled, the reaction mixture was filtered to remove a small
quantity of insoluble substances, evaporated to dryness to remove THF,
and recrystallized with ethyl acetate to obtain a white solid (4.5 g).
1H NMR (DMSO-d6): δ 7.15 (d, 1H, J=3 Hz), 4.26-4.19 (m,
1H), 2.76-2.67 (m, 1H), 2.49-2.47 (m, 1H), 2.01-1.91 (m, 2H).

Example 9

3-aminopiperidine-2,6-dione trifluoroacetic acid

##STR00087##

[0176] 2.28 g of tert-butyl 2,6-dioxopiperidin-3-yl carbamate was
suspended in 30 mL of DCM, and 10 mL TFA was added. The reaction mixture
was stirred at room temperature for 4 h, and was evaporated to dryness to
remove the solvent. 2.4 g of a solid were obtained.

[0178] To a 250 mL round bottom flask equipped with an electromagnetic
stirrer, 14.6 g of glutamine, 60 mL of water, and 60 mL of TFA were
added. When glutamine fully dissolved, the reaction mixture was cooled on
an ice bath to between 0 and 5° C., and 15.4 g of
theino(3,4-c)furan-1,3-dione was added. At the above temperature, the
reaction mixture was allowed to react for 30 min. The reaction mixture
was then allowed to warm to room temperature and allowed to react for
additional 4 h. The reaction mixture was stripped of solvent in vacuo at
85° C. over 4 h to obtain a tacky solid (28 g). The solid was
dissolved in 140 mL of anhydrous THF, and 20 g of CDI and a catalytic
quantity of DMAP were added and allowed to react at a reflux for 6 h
until a large amount of white solid precipitated. The white solid was
cooled and filtered to yield 18 g of dried title compound. 1H NMR
(DMSO-d6): δ 11.10 (s, 1H), 8.26 (s, 2H), 5.03 (dd, 1H, J=3
Hz, J=3 Hz), 2.87-2.82 (m, 1H), 2.66-2.55 (m, 2H), 2.07-2.04 (m, 1H); MS
(m/z): 263 (M-1).sup.+.

[0180] 1.54 g thieno(3,4-c)furan-1,3-dione was dissolved in 20 mL of
anhydrous THF, and 12.8 g of 3-aminopiperidine-2,6-dione was added. The
reaction mixture was allowed to react at room temperature for 4 h. Then,
2 g of CDI and a catalytic quantity of DMAP were added, and the reaction
mixture was allowed to reflux for 6 h until a large amount of white solid
precipitated. The solid was cooled and filtered to yield 2.1 g of the
title product.

[0182] 1.54 g thieno(3,4-c)furan-1,3-dione and 1.42 g of
3-aminopiperidine-2,6-dione trifluoroacetic acid were dissolved in 15 mL
of acetic acid. The reaction mixture was refluxed overnight, cooled, and
evaporated to remove the solvent. The residue was dissolved in 20 mL
anhydrous THF, and 2 g of CDI, and a catalytic quantity of DMAP were
added. The reaction mixture was refluxed for 6 h until a large amount of
white solid precipitated. The solid was cooled and filtered to yield 1.9
g of the title compound.

[0198] 0.309 g of
1-nitro-5-(2,6-dioxopiperidin-3-yl)-5H-thieno(3,4-c)pyrrole-4,6-dione was
dissolved in 10 mL of acetone, and a solution obtained by dissolving
0.783 g Na2S2O4 in 10 mL water was added. The reaction
mixture was refluxed for 2 h, cooled, and 10 mL of water were added. The
aqueous phase was extracted with ethyl acetate (3×50 mL). The
organic phases were combined, washed with 40 mL of water and 40 mL of
brine, dried over anhydrous MgSO4, filtered, evaporated to dryness.
The remaining residue was purified on silica gel column chromatography to
obtain a solid (0.145 g).

[0200] 0.309 g of
1-nitryl-5-(2,6-dioxopiperidin-3-yl)-5H-thieno(3,4-c)pyrrole-4,6-dione
was suspended in 20 mL of ethanol and 20 mL of water, and 0.7 g
freshly-activated iron powder (washed with water after hydrochloric acid
treatment) and 5 mL acetic acid were added and refluxed for 2 h. The
reaction mixture was cooled and filtered. The filtered solution was
evaporated to dryness; and the remaining residue was dissolved in 150 mL
of ethyl acetate, washed with 40 mL of water and 40 mL of brine, dried
over anhydrous MgSO4, filtered, and evaporated to dryness. The
remaining residue was purified on silica gel column chromatography to
obtain a solid (0.095 g).

[0202] 0.084 g of
1-amino-5-(2,6-dioxopiperidin-3-yl)-5H-thieno(3,4-c)pyrrole-4,6-dione was
dissolved in 10 mL of DMF, and 0.5 mL of methyl iodide were added. The
reaction mixture was heated to 80° C., allowed to react at that
temperature for 6 h, cooled, and 100 mL of water were added. The reaction
solution was extracted with ethyl acetate

1-dimethylamino-5-(2,6-dioxopiperidin-3-yl)-5H-thieno(3,4-c)pyrrole-4,6-di-
one

##STR00101##

[0205] 0.084 g of
1-amino-5-(2,6-dioxopiperidin-3-yl)-5H-thieno(3,4-c)pyrrole-4,6-dione was
dissolved in 10 mL of DMF, and 0.5 mL of methyl iodide was added. The
reaction mixture was heated to 80° C., reacted at that temperature
for 6 h, cooled, and then 100 mL of water were added. The reaction
mixture was extracted with ethyl acetate (3×30 mL). The organic
phases were combined, washed with 30 mL of water, and 30 mL of brine,
dried over anhydrous MgSO4, filtered, and evaporated to dryness. The
remaining residue was purified on silica gel column chromatography to
obtain a solid (0.024 g). MS (m/z): 308 (M+1).sup.+.

[0209] 1.54 g of thieno(3,4-c)furan-1,3-dione was dissolved in 20 mL of
anhydrous THF, and 1.42 g of 3-amino-3-methylpiperidin-2,6-dione was
added. The reaction mixture was allowed to react at room temperature for
4 h, and 2 g of CDI and a catalytic quantity of DMAP were added. The
reaction mixture was allowed to reflux for 6 h during which time a solid
precipitated. The reaction solution was cooled and filtered to obtain a
white solid (2.2 g). MS (m/z): 278 (M).sup.+.

[0211] 1.99 g of 2-nitrothieno(3,4-c)furan-1,3-dione was dissolved in 20
mL of anhydrous THF, and 1.42 g of 3-amino-3-dioxopiperidin-2,6-dione
(prepared by a method described in Bioorg. Med. Chem. Lett. 1999, 9,
1625.) was added. The reaction mixture was allowed to react at room
temperature for 4 h, and 2 g of CDI and a catalytic quantity of DMAP were
added. The reaction mixture was refluxed for 6 h during which time a
solid precipitated. The reaction solution was cooled and filtered to
obtain a white solid (1.5 g). MS (m/z): 322 (M-1).sup.+.

[0213] 0.323 g of
1-nitro-5-(3-methyl-2,6-dioxopiperidin-3-yl)-5H-thieno(3,4-c)pyrrole-4,6--
dione was dissolved in 10 mL of acetone, and a solution obtained by
dissolving 0.783 g Na2S2O4 in 100 mL of water was added.
The reaction mixture was refluxed for 2 h, cooled, and 100 mL of water
were added. The aqueous phase was extracted with ethyl acetate
(3×50 mL), the organic phases were combined and washed with 40 mL
of water and 40 mL of brine, dried over anhydrous MgSO4, filtered,
and evaporated to dryness. The remaining residue was purified on silica
gel column chromatography to obtain a solid (0.156 g). MS (m/z): 292
(M-1).sup.+.

Example 28

Tert-butyl 1-methyl-2,6-dioxopiperidin-3-yl carbamate

##STR00106##

[0215] 0.228 g of tert-butyl 2,6-dioxopiperidin-3-yl carbamate was
dissolved in 10 mL of DMF, and 0.036 g of NaH (95%) were added. The
reaction mixture was allowed to react at room temperature for 30 min, and
0.2 mL of CH3I were added. The reaction mixture was allowed to react
overnight. Then, 100 mL of water were added and the aqueous phase was
extracted with ethyl acetate (3×30 mL). The organic phases were
combined and washed with 30 mL of water and 30 mL of brine, dried over
anhydrous MgSO4, filtered, and evaporated to dryness. The remaining
residue was purified on silica gel column chromatography to yield a solid
(0.186 g).

Example 29

1-methyl 3-aminopiperidine-2,6-dione trifluoroacetic acid

##STR00107##

[0217] 0.242 g of tert-butyl 1-methyl-2,6-dioxopiperidin-3-yl carbamate
was dissolved in 10 mL of DCM, and 3 mL of TFA were added. Then, the
mixture was stirred at room temperature for 4 h. The reaction mixture was
evaporated to dryness, and a solid was obtained (0.253 g).

[0219] 0.199 g of 2-nitrothieno(3,4-c)furan-1,3-dione was dissolved in 20
mL of anhydrous THF, and 0.256 g of 1-methyl-3-aminopiperidin-2,6-dione
trifluoroacetate and 0.1 mL of TFA were added. The reaction mixture was
allowed to react at room temperature for 4 h, and then 0.2 g of CDI and a
catalytic quantity of DMAP were added. The reaction mixture was allowed
to react for 6 h, cooled and evaporated to dryness. The remaining residue
was dissolved in 80 mL of ethyl acetate, washed successively with 40 mL
of 1N HCl, 40 mL of water, and 40 mL of brine, dried over anhydrous
MgSO4, filtered, and evaporated to dryness. The remaining residue
was separated on silica gel column chromatography to yield a solid (0.103
g). MS (m/z): 322 (M-1).sup.+.

[0221] 0.097 g of
1-nitro-5-(1-methyl-2,6-dioxopiperidin-3-yl)-5H-thieno(3,4-c)pyrrole-4,6--
dione was dissolved in 10 mL of acetone; and a solution obtained by
dissolving 0.239 g of Na2S2O4 in 10 mL of water was added.
The reaction mixture was refluxed for 2 h, cooled, and 10 mL of water
were added. The aqueous phase was extracted with ethyl acetate
(3×30 mL), the organic phases were combined, washed with 40 mL of
water and 40 mL of brine, dried over anhydrous MgSO4, filtered, and
evaporated to dryness to remove the solvent. The remaining residue was
purified on silica gel column chromatography to yield a solid (0.046 g).
MS (m/z): 292 (M-1).sup.+.

Patent applications by Hesheng Zhang, Tianjin CN

Patent applications by TIANJIN HEMAY BIO-TECH CO., LTD

Patent applications in class Plural hetero atoms in the polycyclo ring system

Patent applications in all subclasses Plural hetero atoms in the polycyclo ring system